Various methods are used to measure a distance to a subject. For example, a method of using light in order to measure a distance to a subject is widely used. Examples of a method of measuring a distance by using light include a triangulation method, a time-of-flight (TOF) method, and a phase-shift method.
The triangulation method is a method of measuring a distance by using triangulation, and the TOF method is a method of calculating a distance by using a difference between a time when light is emitted from a distance measuring apparatus and a time when the light returns to the distance measuring apparatus after being reflected from a subject. The phase-shift method is a method of calculating a distance based on phase-shift between reference light and light that has returned to a distance measuring apparatus after being reflected from a subject due to irradiation of light having a uniform frequency to the subject.
Alternatively, a method of measuring a distance to a subject by using a plurality of images obtained through a plurality of cameras may be used. For example, stereo matching using a stereo camera is a process of recognizing a 3-dimensional (3D) structure by using two eyes of a person, which is realized in terms of hardware, and is a method of extracting information about a depth (or a distance) in a space through a process of analyzing a pair of images obtained by photographing one subject using two cameras. By calculating a value obtained from an input image, 3D distance information of an observation space may be measured.
However, according to such general technologies, complicated hardware structures are required while irradiating and receiving special light or using a plurality of cameras.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.